Currently, LTE-A (Long Term Evolution-Advanced) system can support CA (Carrier Aggregation) of five carriers at most, and one LTE-A UE (User Equipment) needs to feed back the ACK (ACKnowledgement)/NACK (Non-ACKnoledgement) feedback information corresponding to multiple downlink carriers and downlink sub-frame in the same uplink sub-frame. In order to avoid inconsistent understanding between eNB (eNodeB) and UE toward ACK/NACK codebook during packet loss, the ACK/NACK codebook to be fed back by UE on one uplink sub-frame shall be generated based on the maximum configuration: for FDD (Frequency Division Duplex) system, ACK/NACK codebook is decided by the total number of configured downlink carrier and the transmission mode of each downlink carrier, viz. UE needs to feed back N+N1 bit ACK/NACK in one uplink sub-frame, wherein N refers to the total number of configured downlink carrier number and N1 is the downlink carrier number with transmission mode of multi-codeword; as for TDD (Time Division Duplex) system, ACK/NACK codebook depends on the total number of configured downlink carrier number, transmission mode of each downlink carrier and the total number of downlink sub-frame of UE performing ACK/NACK feedback on the same uplink sub-frame, viz. UE shall feed back M×(N+N1) bit ACK/NACK on one uplink sub-frame, wherein M refers to the total number of downlink sub-frame number performing ACK/NACK feedback on the same sub-frame, for different uplink/downlink configuration and uplink sub-frame, M varies, viz. number of K in each column of Table 1. Besides, M may be different for various carriers, then UE shall feed back
      ∑          i      =      1        N    ⁢          ⁢            C      i        ·          M      i      bit ACK/NACK in one uplink sub-frame, wherein, Ci is the codeword number corresponding to the transmission mode of carrier i, Ci=1 for single codeword transmission mode and Ci=2 for multi-codeword transmission mode is, Mi refers to the total number of downlink sub-frame performing ACK/NACK feedback on the same uplink sub-frame on carrier i, which is decided by uplink/downlink configuration of carrier i. As for downlink carrier and/or downlink sub-frame position without scheduling in the AK/NACK codebook, NACK/DTX (Discontinuous Transmission) will be generated as feedback information.
TABLE 1Downlink Association Set Index K: {k0, k1, . . . kM-1} for TDDUplink/Downlinkconfig-Sub-frame number nuration01234567890——6—4——6—41——7, 64———7, 64—2——8, 7, 4, 6————8, 7,——4, 63——7, 6, 116, 55, 4—————4——12, 8, 7, 116, 5,——————4, 75 ——13, 12, 9, 8, ———————7, 5, 4, 11, 66——775——77—
In order to support larger ACK/NACK codebook transmission, LTE-A system defines a new PUCCH (Physical Uplink Control Channel) transmission format PUCCH format 3. It at most supports 20 bits ACK/NACK feedback, as shown in FIG. 1. When the ACK/NACK information to be fed back by UE exceeds the aforementioned threshold, bundling shall be performed on ACK/NACK information, to make the codebook smaller than or equal to the aforementioned threshold, such as Spatial Bundling, Time-Domain Bundling or Frequency-Domain Bundling. PUCCH format 3 adopts different coding methods for different ACK/NACK codebooks. When ACK/NACK codebook is less than or equal to 11 bits, the RM (Reed-Muller) encoding of Rel-8 (Release-8) system is reused, viz. the ACK/NACK feedback bits shall be encoded into 48-bit coded bits through RM(32,O)+Repetition encoding method; when ACK/NACK codebook is larger than 11 bits, Dual-RM encoding method is adopted, as shown in FIG. 2, first the ACK/NACK feedback bits shall be divided into two groups averagely, then the ACK/NACK feedback bits of each group shall be encoded into 24-bit coded bits by adopting RM (32, O)+(Truncation) encoding method.
PUCCH power control in LTE-A system shall follow the power control method of LTE Rel-8/9 system as much as possible. The formula of defining PUCCH power control is as below:
                                          P            PUCCH                    ⁡                      (            i            )                          =                  min          ⁢                                    {                                                                                                                                            P                                                      CMAX                            ,                            c                                                                          ⁡                                                  (                          i                          )                                                                    ,                                                                                                                                                          P                                                  0                          ⁢                          _PUCCH                                                                    +                                              PL                        C                                            +                                              h                        ⁡                                                  (                                                                                    n                              CQI                                                        ,                                                          n                              HARQ                                                        ,                                                          n                              SR                                                                                )                                                                    +                                                                        Δ                          F_PUCCH                                                ⁡                                                  (                          F                          )                                                                    +                                                                        Δ                                                      T                            ×                            D                                                                          ⁡                                                  (                                                      F                            ′                                                    )                                                                    +                                              g                        ⁡                                                  (                          i                          )                                                                                                                                }                        ⁢                                                  [                          dB              ⁢                                                          ⁢              m                        ]                                              (        1        )            Wherein: PCMAX,c is the allowable maximum transmit power of carrier c, viz. for PUCCH it is the allowable maximum transmit power of the primary uplink carrier; PLc refers to path loss compensation value of carrier c, which is obtained by downlink carrier measurement of higher layer configuration;
PO_PUCCH represents the target value of transmit power, composed of cell-specific part PO_NOMINAL_PUCCH and UE-specific part PO_UE_PUCCH of higher layer configuration; h(nCQI, nHARQ, nSR) refers to the power offset corresponding to the number of various bits sent by PUCCH; wherein, nCQI corresponds to the number of CSI (Channel State Information) bit sent, CSI includes CQI (Channel Quality Indicator) information, PMI (Precoding Matrix Indicator) information, RI (Rank Indication) information, PTI (Precoding Type Indicator) information, etc., nHARQ corresponds to the number of ACK/NACK bit sent, and nSR{0,1} represents whether SR (Scheduling Request) transmission exists in the current uplink sub-frame; Configured by higher layer, ΔF_PUCCH(F) represents the power offset of different PUCCH formats relative to the PUCCH format 1a, the PUCCH formats include PUCCH format 1/1a/1b/2/2a/2b, PUCCH format 3 and other various formats, which is a further compensation to h(nCQI, nHARQ, nSR) power control error; ΔTxD(F′) is configured by higher layer, with independent configuration for each PUCCH format, representing the power offset of different PUCCH formats with multi-antenna port transmission (viz. transmission diversity in Rel-10) mode;
g(i) is the accumulation of the power control commands.
Among all parameters mentioned in formula (1), the value of h(nCQI, nHARQ, nSR) can be:
h(nCQI, nHARQ, nSR)=0 for PUCCH format 1a/1b;
As for PUCCH format 1b with channel selection (PUCCH format 1b based on channel selection), if multiple carriers are configured for UE,
            h      ⁡              (                              n            CQI                    ,                      n            HARQ                    ,                      n            SR                          )              =                  (                              n            HARQ                    -          1                )            2        ,if only one carrier is configured for UE, h(nCQI, nHARQ, nSR)=0;
For PUCCH format 2/2a/2b,
      h    ⁢          (                        n          CQI                ,                  n          HARQ                ,                  n          SR                    )        =      {                                        10            ⁢                                                  ⁢                                          log                10                            ⁡                              (                                                      n                    CQI                                    4                                )                                                                                        if              ⁢                                                          ⁢                              n                CQI                                      ≥            4                                                0                          otherwise                    with normal CP (Cyclic Prefix) and
      h    ⁢          (                        n          CQI                ,                  n          HARQ                ,                  n          SR                    )        =      {                                        10            ⁢                                                  ⁢                                          log                10                            ⁡                              (                                                      n                    CQI                                    4                                )                                                                                                        if                ⁢                                                                  ⁢                                  n                  CQI                                            +                              n                HARQ                                      ≥            4                                                0                          otherwise                    with extended CP;
As for PUCCH format 3,
      h    ⁡          (                        n          CQI                ,                  n          HARQ                ,                  n          SR                    )        =                              n          HARQ                +                  n          SR                -        1            2        .  
As the ACK/NACK codebook determined by UE based on its own configuration is always larger than the number of data package actually received by UE, esp. when multiple carriers are configured for UE, but eNB only schedules few or one carrier/sub-frame, the number of effective ACK/NACK bits (ACK/NACK codebook corresponding to the data packages actually received by UE or those with actual scheduling) in the ACK/NACK codebook is much less than the total bit number of the ACK/NACK codebook, and eNB can only detect the effective information part according to detail scheduling status, to improve detection performance, therefore, h(nCQI, nHARQ, nSR) shall be calculated based on the effective codebook of UE: for ACK/NACK transmission without bundling scheme, it is agreed that nHARQ is determined based on number of the TB (Transport Block) actually received by UE and the number of the PDCCH indicating downlink SPS (Semi-Persistent Scheduling) resource release, so as to guarantee that the transmit power of UE in PUCCH corresponds to the number of downlink carrier and downlink sub-frame with actual scheduling, thus avoiding power waste; as for ACK/NACK transmission with bundling, the number of bits of bundled information actually transmitted by UE is smaller than the number of the TB actually received, so nHARQ shall be determined in accordance with the bundled codebook, to avoid UE power waste and reduce interference.
In the procedure of realizing the objects of the present invention, at least the following problems existing in the current technologies were found:
Considering that PUCCH format 3 adopts different RM encoding mode under different ACK/NACK codebooks, when ACK/NACK codebook is larger than 11 bits, ACK/NACK feedback information shall be divided into two groups, due to the randomization of eNB scheduling, the effective ACK/NACK bits in the ACK/NACK codebook cannot be certainly divided to each group uniformly, therefore ACK/NACK effective encoding rate of each group of RM encoding is different, thus reducing ACK/NACK detection performance. As shown in FIG. 3, when ACK/NACK codebook[b0, b1, . . . b11] is divided into two groups at the middle position of the codebook, all 6 bits in group I [b0, b1, . . . b5] are effective information, which means that the effective encoding rate is 6/24, in group II [b6, b7, . . . b11], only b6 and b7 are effective information and other bits refer to occupation information generated by UE, which means that the effective encoding rate is 2/24, thus reducing the overall ACK/NACK transmission performance. Grouping is not required for single-RM encoding, so performance reduction due to unbalanced effective information grouping does not exist.
Besides, PUCCH format 3 supports multi-antenna port transmission mode, and 2 antenna ports in Rel-10 adopts SORTD (Spatial Orthogonal Resource Transmit Diversity) as the transmission diversity scheme. Differences of transmission performance exist in SORTD and single-antenna port transmission.
It can thus be seen that, PUCCH format 3 adopts single-RM and Dual-RM to cause differences on transmission performance of different number of effective bits, and PUCCH format 3 also adopts a single-antenna port transmission mode and a multi-antenna port transmission mode to cause differences on transmission performance of different number of effective bits. The existing technologies have not yet proposed solutions of improving ACK/NACK transmission performance by improving accuracy of power control specific to such differences.